The chief medical officer, Professor Chris Whitty, and chief scientific adviser, Sir Patrick Vallance, agreed that the action was needed urgently after the number of positive cases rose steeply.
Where do these rules apply?
The rule of six applies across England to all ages and to indoor and outdoor gatherings, depending, most crucially, on what tier your area is in.
This includes private homes, parks, pubs, restaurants and sporting events.
In Tier 1, you cannot sit at a pub or restaurant table with more than five friends at any given time. In Tier 2 and above, you may not meet anybody indoors beyond your home or support bubble.
What are the exemptions?
Households or support bubbles of more than six people are exempt from the new rules. Support bubbles allow adults who live by themselves and single parents with children under 18 to join up with one other household.
Under new rules, parents with babies under the age of one can also form a “support bubble” with another household.
This means they can do things such as visit their house, stay the night and travel together in vehicles.
Weddings are allowed to go ahead, with ceremonies and receptions of up to 15 people permitted. However, Mr Johnson made clear that they must be conducted in a Covid-secure way. Guests have to stand or sit at least one metre apart, and take other safety precautions.
Funerals can continue, with 30 people allowed to pay their respects. The Government previously faced criticism at the outset of the pandemic when guidance limited mourners to groups of between five and 10.
Funeral directors accused councils of misinterpreting lockdown rules by banning family members from crematoria and graveyards and going “way beyond” their legal powers.
Matt Hancock said he regretted the move because it meant that “in the peak of the pandemic, lots of people didn’t go to the funeral even of someone they’ve been married to for 50 years”.
Other linked commemorative events such as wakes or stonesettings are limited to 15 attendees.
Schools and offices
Schools and workplaces continue to operate under existing Covid guidelines, which include year groups being kept in bubbles, classrooms reconfigured and masks worn in communal areas.
However, the Prime Minister has encouraged people to work at home wherever possible.
Read more: Will schools close again?
Pubs and restaurants
In Tier 1 areas, groups are limited to six, however, Covid-secure hospitality venues are able to hold larger numbers of people. They are legally required to request test and trace information from customers and keep the details for 21 days.
All pubs, bars and restaurants must now operate a table service only, except for takeaways. Together with all hospitality venues, they must close at 11pm.
Places of worship
Churches, synagogues, mosques and temples remain open, although congregations are required to stay at least one metre apart. Under the existing guidance, services are expected to conclude as quickly as possible, with worshippers encouraged to leave “promptly” afterwards.
It came after the Archbishop of Canterbury confirmed that the rule of six would not apply to churches, writing on Twitter: “Worship is the work of God – not a social gathering – and gives the strength to love and serve.”
However, the government have confirmed that between December 23 and 27, you can attend places of worship with your Christmas bubble. This applies across all tiers.
All adult team sport events are forced to legally abide by the rule of six with only six players now allowed to play at any one time. This includes indoor five-a-side football matches and the planned return of spectators to sports venues.
Santa grottos are allowed to open across all tiers, provided they take place in venues that are permitted to open under the new restrictions, whilst ensuring that “appropriate Covid-secure measures” have been put in place, such as social distancing.
New government guidance has stated that door-to-door carol singing and carol services are also allowed to take place as long as the Rule of Six is followed. The government has also suggested principles for safer singing which must be followed should these performances take place.
Nativity plays are also permitted to go ahead within school bubbles. However, if the performance takes place in an area under Tier 3 restrictions, then it must be viewed as a recording or via a live stream.
Volunteering during the festive period has also been allowed to take place, but similar to the rules around working, this must be done from home where possible.
Rules on shopping, whether indoors or outdoors, including Christmas Markets, remain in place throughout the holidays, dependent on tier level. This includes the Boxing Day Sales.
The Government has been criticised after granting grouse shooting a special exemption from the rule of six.
Hunting with guns is included on a list of sports, pursuits and outdoor activities where groups of up to 30 people are allowed to gather, despite the introduction of the new restrictions.
It is understood the exemption was granted after the Cabinet Office’s special Covid-19 Operations ministerial committee organised a meeting to specifically discuss hunting and shooting.
Will there be an exception at Christmas?
Boris Johnson confirmed on December 16, that plans to allow families to meet this Christmas will still go ahead, but has urged people to “exercise extreme caution” as they celebrate Christmas amid fears about the spread of coronavirus.
Michael Gove met virtually with the leaders of the devolved administrations on December 15 to discuss the four-nation ‘Christmas bubble’ plan, amid growing pressure to scrap household mixing over the festive period.
The meeting comes after two British medical journals urged the Government to reverse the “rash” five-day Christmas break, or face a surge in hospital admissions.
Those talks have led to an agreement amongst the four nations to continue with the plan, but with a stronger message warning people of the dangers.
Mr Johnson told MPs at Prime Minister’s Questions there was “unanimous agreement” across the four nations “that we should proceed in principle with the existing regulations”.
“We don’t want to criminalise people’s long-made plans,” he said.
“But we do think it’s absolutely vital that people should – at this very, very tricky time – exercise a high degree of personal responsibility, especially when they come into contact with elderly people, and avoid contact with elderly people wherever possible.”
The current rules, agreed by ministers, are a UK-wide plan to allow three households to mix for five days between December 23 and 27, subject to a vote in parliament and each of the devolved administrations.
Northern Ireland has negotiated a seven-day suspension of the rules to allow for people who need to catch flights or ferries to the mainland. It will run from December 22 to 28.
However, Wales has set a two household limit for mixing during Christmas, which will be made into law, the Welsh Government has confirmed.
This news comes only hours after the First Minister stated that lowering the number of homes that can form a Christmas bubble from three to two was guidance rather than a requirement.
Families must decide on their extended bubbles in advance and will not be able to mix with anyone from outside that bubble during the festive break. Rules on who you can meet in pubs, bars and restaurants over the Christmas period will not change from the current tier restrictions.
Will I be punished for breaking the rules?
The Government hopes the new rules will be more simple for people to understand. It will also make it easier for the police to break up large gatherings.
Failure to stick to the new rules could mean a £200 fine, which will double with every subsequent offence up to £3,200.
What are the rules in other parts of the UK?
Different rules apply to social gatherings elsewhere in the UK.
Scotland is currently working with a five level system. The 11 regions which were placed in Level 4 at the start of the new system, which included Glasgow, have moved down to Level 3, with non-essential shops and businesses being allowed to open again. This includes pubs, bars and restaurants, although rules vary for each level.
Northern Ireland ended its circuit breaker lockdown on December 10, with non-essential shops as well as hospitality venues (excluding pubs which do not serve food) being allowed to open their doors. The decision to impose the circuit breaker was put in place following the news that three intensive care units in the country were full at the end of November.
In Wales, tighter Covid restrictions began on December 4 as a rise in Coronavirus cases was recorded. Pubs, bars and restaurants will have to close from 6pm and mst not serve alcohol at any time. The Welsh government announced detail of a four-tier traffic light system on December 11, stating that the country will enter Tier 4 from December 28, if there is no decrease in cases in the country, resulting in a full lockdown. The full coronavirus control plan will be announced and voted on in the week of December 14.
How can we socialise safely?
A campaign was launched to encourage people to help stop the spread of coronavirus because people are more likely to socialise indoors during autumn and the winter.
The Hands Face Space campaign urges people to ensure they wash their hands, use a mask where appropriate and stay at least two metres apart – or one metre with a face covering or other precautions.
The campaign states that these are the three most effective ways the public can contain the spread of the virus.